First of all, what box can you fit in your vehicle? And what the heck vehicle are you driving? And what amplifier will drive the subs?

What kind of music do you want to play? And especially, HOW LOUD? You must be brutally honest about this-many people say "oh, it doesn't have to be that loud" and are then sad-faced when they can't be heard 3 blocks away. Some talk about accuracy but really deep down are looking for that chest pounding feel.

It's then helpful if you call out some specific model numbers, and ideally a link to some Thiele-Small parameters-or better yet, post them into the thread. Then we can look at those subs vs. what you said about the box vs. what you said about the sound and see if either is compatible. We might be able to find those things but if you do it first more people will respond.

I can tell you Rockford and Alpine test the heck out of their subs; I have no idea how much testing DC and Memphis.

First of all, what box can you fit in your vehicle? And what the heck vehicle are you driving? And what amplifier will drive the subs?

What kind of music do you want to play? And especially, HOW LOUD? You must be brutally honest about this-many people say "oh, it doesn't have to be that loud" and are then sad-faced when they can't be heard 3 blocks away. Some talk about accuracy but really deep down are looking for that chest pounding feel.

It's then helpful if you call out some specific model numbers, and ideally a link to some Thiele-Small parameters-or better yet, post them into the thread. Then we can look at those subs vs. what you said about the box vs. what you said about the sound and see if either is compatible. We might be able to find those things but if you do it first more people will respond.

I can tell you Rockford and Alpine test the heck out of their subs; I have no idea how much testing DC and Memphis.

Lol apparently people don't read signatures......
Buick skylark 1995 custom, 4 door.
Hifonics 2000 rms amp
Music played: Techno, Dubstep, Heavy bass rap, Metal, Hard rock.
VERY LOUD. Just bought all mid range speakers for the inner car...so it's pretty much all treble in the inside all bass in the back.
Right now I have that chest pounding feeling, but I want that "HOLY CRAP, Let's get the hell away from this car cuz it's so LOUD" feeling. lol I want to make everyone stay away from my car =P
...and once again, I DID call out some models... 2 12" level 3 DC subs...http://www.dcsoundlab.com/woofers.html

More seriously, if you want to play really loud, why would you downgrade your amp? If you want significantly more SPL, you'll need significantly more power. It doesn't say what model Hifonics you have, but in real life only a handful of amps truly deliver more dynamic power when loaded down more.

Of course, the speakers can make a tremendous difference in the SPL per watt. But it depends on the box design and how it interacts with the car-congratulations, you are entering the realm of voodoo!

Your Skylark trunk is really that small? Or is some of it already taken up by an enclosure?

As for Memphis vs. DC, do your DCs bottom out? Their basket sure looks like one that was very popular back in the day. A good basket, but ultimately limiting of excursion. The Memphis sure looks beefy, but hard to tell if the output lives up to that.

You might want to consider a big vented pro driver, like some JBL 18" or such, if you can sacrifice the box space. Might give you more SPL per watt at the low frequencies. Rockford's* stuff is actually built as tough as pro drivers, but auto subs are generally designed to fit in smaller boxes and so maybe don't have as much SPL per watt. I'd have to dig out my LEAP simulator from mothballs and make some runs with specific parameters to check that statement-it's possible that over a narrow low frequency range the car subs might equal the sensitivity of the pro driver.

I'm wondering if you should be looking at some kind of a folded or tapped horn.

*I'm just referring to them from a visit I made there; their guys were doing teardowns on failures from several-THOUSAND-watt RMS power testing, actually more than many pro concert sound drivers used to be able to handle. I mentioned JL before just because I know they're in the same league; MTX and some others certainly have the resources to test like that but I can't say if they do. The small companies usually don't have the resources to do really extensive power testing, but it doesn't mean their stuff won't hold up.